CO2 to ethanol: A selective photoelectrochemical conversion using a ternary composite consisting of graphene oxide/copper oxide and a copper-based metal-organic framework

Abstract

Photoelectrochemical conversion of CO2 to chemicals has been acknowledged as an advanced and promising approach for the mitigation of carbon dioxide that is a greenhouse gas. However, so far it has mainly been confined to the generation of C1 products like formate, CO, methanol etc. and very few reports are known on the generation of ethanol or higher alcohols. The present work described an efficient PEC reduction of CO2 to ethanol selectively by using a photocathode consisting of a ternary composite containing CuxO/GO and a copper-based metal-organic framework (Cu-MOF). The maximum ethanol yield was found to be 162 uM cm−2 after 4 h at an applied potential of -0.5 V vs Ag/AgCl. The better charge separation, higher mobility and density of photogenerated charge carriers on the interface of nanocomposite led to the higher availability of photo-electrons for CO2 reduction that is further confirmed by the DFT studies. Furthermore, DFT calculations suggested the binding of CO2 over GO/CuxO/Cu-BTC surface via Cu-atoms through the vertical orientation that brought the CO2 molecules closer to the composite and therefore is considered as the most favourable adsorption configuration.